This proposal is for the Pennsylvania College of Optometry Clinical Center to continue to annually examine the 93 currently enrolled COSMICC participants (only 15 subjects have been lost to follow-up since enrolled in 1997-98) at the Pennsylvania College of Optometry center for an additional 5 yrs (total follow-up, 14 yrs) following the COSMICC2 protocol. The data collected from this center will be used to address the specific aims described in more detail in the Chair application and summarized briefly here: 1) to use mathematical functions (the Gompertz function and others) to model myopia progression in the 58% of COSMICC subjects with progressing myopia and to develop predictive models and test hypotheses based on previously identified risk factors (age, ethnicity, parental myopia); 2) to test 4 hypotheses related to environmental risk factors for myopia progression and stabilization and axial elongation in this well-characterized cohort of myopes; and 3) to test three hypotheses related to risk factors for the development of myopia-related changes in IOP, CCT and macular thickness in COSMICC subjects. The high prevalence of myopia (25% of the US adult population) and its prominence as a public health problem (risk factor for conditions that can cause vision loss and blindness) emphasize the importance of gaining increased understanding of mechanisms underlying progression and eventual stabilization, so that in the future myopia might be limited to low levels. Better understanding of the factors predictive of myopia progression and stabilization also will help guide selection and timing of interventions as well as target those groups that may benefit the most from treatment. This application documents the Pennsylvania College of Optometry's ability to follow the COSMICC2 Manual of Procedures and to retain patients for five years. Documentation is also provided that the Pennsylvania College of Optometry has the personnel, equipment, and facilities to conduct the study in accordance with the COSMICC2 Manual of Procedures.